Click on the Zoom icon  
 
On your Zoom Home page, click on settings 

Click on Statistics                 Zoom Version

If the Version line is not at least version 5.1.3, you will need to update Zoom.
See the “How to Update Zoom” article: 
https://cbc.teamdynamix.com/TDClient/1860/Portal/KB/ArticleDet?ID=104129
 
If the Version line is blank, please follow these directions to uninstall Zoom: 
 https://cbc.teamdynamix.com/TDClient/1860/Portal/KB/ArticleDet?ID=104811
Once that is done, follow these directions to reinstall Zoom: 
https://cbc.teamdynamix.com/TDClient/1860/Portal/KB/ArticleDet?ID=85196
After that, Zoom should let you update whenever a new update comes out.